1. Technical Field
The present invention relates to the technical field of on-load tap-changers of transformers, and particularly to a change-over structure between a moving contact and a static contact of a tap selector of a hanged combined-type on-load tap selector.
2. Related Art
For an on-load tap-changer, in the case that a transformer is on load, that is, is uninterrupted, a turn ratio of a primary winding to a secondary winding of the transformer is changed by changing winding taps connected to the transformer, so as to achieve the purpose of changing an output voltage of the transformer.
A combined-type on-load tap-changer is divided into two parts in terms of functions, that is, a change-over changer and a tap selector. As shown in FIG. 1, the upper part is a change-over changer A, and the lower part is a tap selector B. The resistor R is a transitional resistor. A main tap winding b of the transformer is serially connected to a main winding a of the transformer, the main tap winding b of the transformer has taps 1-12, where the taps 1, 3, 5, 7, 9, and 11 are located at an odd side and the taps 2, 4, 6, 8, 10, and 12 are located at an even side. As shown in FIG. 1, the selector is conductive at the position of the tap 3 at the odd side, and the tap 2 or tap 4 of the even side may be pre-selected in the non-conduction case. When the upper change-over changer is changed over to the right side, that is, the even side, the tap 2 or the tap 4 is conductive, thereby changing the number of turns of the winding of the transformer, and changing the turn ratio of the primary winding to the secondary winding of the transformer.
Referring to FIG. 2, the conventional combined-type on-load tap-changer selector adopts two concentrically rotating circle structures of equal diameter with a certain interval in an axial direction, where in one circle, static contacts connected to winding taps of the odd taps 1b, 3b, 5b, 7b, 9b, and 11b are circularly arranged, and in the other circle, static contacts connected to winding taps of the even taps 2b, 4b, 6b, 8b, 10b, and 12b are circularly arranged. In the conventional transformer, a winding of each phase has 10 to 18 voltage regulating taps. In this way, in each circle structure, 5 to 9 (in most cases, 9) static contacts are distributed, as shown in FIG. 2.
This concentrically rotating structure has a certain advantage in a combined-type on-load tap-changer of a buried vertical structure, but in a combined-type on-load tap-changer hanged and arranged horizontally, leads 1a, 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, and 12a need to be connected to the static contacts 1b, 2b, 3b, 4b, 5b, 6b, 7b, 8b, 9b, 10b, 11b, and 12b of a on-load tap-changer selector on a wiring terminal C of an insulation plate. Since the on-load tap-changer is used in a high-voltage and large current environment, the leads la, 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, and 12a cannot be connected with a flexible wire due to the action of an electromagnetic force, where a circular copper rod needs to be used to be bent and shaped. It can be seen from FIG. 2 that, the leads 1a, 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, and 12a need to be bent to various shapes, so the manufacturing is difficult. Due to an inter-stage voltage, a certain interval needs to be ensured between the leads, so a large space is occupied, and the changer oil chamber needs to be large, that is, the cost of the apparatus is increased, and the consumption of the transformer oil is increased. Due to the action of the electromagnetic force, the positions of the leads are easily changed, easily causing an accident.